Preparation of phosphomolybdic acid coated carbon nanotubes and its supercapacitive properties

Abstract

The phosphomolybdic acid coated carbon nanotubes (PMA@CNTs) were successfully fabricated by a facile polydopamine-assisted impregnation method, in which polydopamine can form an extraordinary adhesive interlayer to homogeneously adhere PMA on the surfaces of CNTs. The composition, structure, morphology and supercapacitive performances of the resulting PMA@CNTs hybrids were systematically characterized by a range of experimental tools including fourier transform infrared spectrometer (FTIR), X-ray diffraction (XRD), X-ray photoelectron spectroscope(XPS), scanning electron microscope(SEM), transmission electron microscope(TEM), cyclic voltammetry (CV) and galvanostatic charge/discharge (GCD). The PMA can homogeneously loaded onto the surface of the CNTs with the aid of superior adhesion of polydopamine. Here, the performance of the resulting PMA@CNTs hybrids as supercapacitor electrodes was investigated in a three-electrode arrangement using an aqueous electrolyte (0.5 mol/L H2SO4). The supercapacitor assembled with the PMA50@CNTs hybrids exhibit the highest specific capacitances (511.7 F/g at 10 mV/s) and maximum energy density of 66.8 Wh/kg at power density of 1000 W/kg, based on the total mass of active materials. In addition, the supercapacitor also has excellent cycling stability retaining>100% of its specific capacitances after 1000 cycles at current density of 5 A/g. These results demonstrate a simple and scalable application of PMA@CNTs hybrids toward electrochemical energy storage.